Nitrogen‐Doped Carbon Dots Prepared via Microchannel Method for Visual Detection of Copper Ions

ABSTRACT Copper ions (Cu 2+ ) play a crucial role in biological processes; however, excessive intake can result in severe health problems. Current methods for detecting copper ions are both expensive and complex. Therefore, there is a need for efficient and straightforward visual detection methods. In this study, novel nitrogen‐doped carbon dots (N‐CDs) were synthesized via a microchannel method using diethylenetriamine and citric acid as precursors and were characterized by TEM, XRD, and IR, among others. The N‐CDs demonstrated high selectivity and strong fluorescence, showing a linear quenching response to copper ions with a detection limit of 46 nM, whereas other common metal ions, such as Ca 2+ and Mg 2+ , exhibited negligible interference even at higher concentrations. These N‐CDs were subsequently applied to test paper, allowing for on‐site visual and quantitative detection of copper ions via a colorimetric method. This approach provides a novel solution for the rapid detection of copper ions, with significant potential in environmental monitoring, public health, and industrial applications.